U.S. Pat. No. 4,817,828 discloses an apparatus for inflating an inflatable vehicle occupant restraint such as an air bag. The apparatus includes an inflator which comprises a source of gas for inflating the air bag. A body of ignitable gas generating material is contained in the inflator. The gas generating material is ignited when the vehicle experiences a condition that indicates the occurrence of a collision for which inflation of the air bag is desired. The collision-indicating condition may comprise, for example, the occurrence of a predetermined amount of vehicle deceleration. As the gas generating material burns, it generates a large volume of gas which is directed to flow from the inflator into the air bag to inflate the air bag. When the air bag is inflated, it extends into the vehicle occupant compartment to restrain an occupant of the vehicle from forcefully striking parts of the vehicle.
The inflator disclosed in the '828 patent has a cylindrical housing. The housing includes an inner tubular wall and an outer tubular wall. A cylindrical filter is contained in the housing concentrically between the tubular walls. The inner tubular wall defines a cylindrical combustion chamber in which the body of gas generating material is contained. A plurality of gas flow openings extend through the inner tubular wall, and thus direct the gas to flow radially outward from the combustion chamber and through the filter toward the outer tubular wall. A plurality of gas flow openings extending through the outer tubular wall similarly direct the gas to flow radially outward from the housing toward the air bag.
In the inflator disclosed in the '828 patent, the housing is closed at its axially opposite ends by a pair of circular end walls. The end walls extend diametrically across the open ends of the tubular walls. Each end wall has an annular peripheral flange, and is held in place by a respective end portion of the outer tubular wall which is crimped around the flange.